BMX riders assembled in Houston for a free downtown event are watching the skies, waiting for a dry patch.

Scheduled to start at 7 p.m. Friday at 1503 Chartres, the free event called Red Bull Urban Rhythm could be delayed until as late as 9:30 p.m., spokeswoman Whitney Gonzales said.

The track must close by 11 p.m., she said.

"We're watching Doppler," Gonzales said of the widely used weather monitoring technology. "It looks like the rain should clear up in time for the event, but we won't put the riders on the course unless it's dry."

If the course isn't dry enough for Friday evening, the event could be delayed until Nov. 23, Gonzales said.

The temporary course of wood ramps and dirt, designed and painted by local artists, measures about 12,700 square feet, organizers said.

The event, termed a "street art BMX project," involves a collaboration of well known rider Mike "Hucker" Clark and Houston graffiti artist GONZO247.

Families are encouraged to bring children, according to promotional material.